1. Field of the Invention
The present invention relates to a vacuum evaporator for coating the surface of a work with a film by depositing a material evaporated from an evaporation source in vacuum atmosphere on the work surface.
2. Description of the Related Art
Arc ion plating (AIP) method is a form of vacuum evaporation method, in which an evaporation source is provided in a vacuum chamber as a cathode to generate vacuum arc discharge with an anode, and a cathode material is evaporated from the evaporation source and accumulated on the surface of a work housed in the vacuum chamber to coat the surface of the work with a film.
Conventional vacuum evaporators for executing the AIP method include, for example, a device disclosed in Japanese Patent No. 3195492. This device comprises a vacuum chamber, a rod-like evaporation source provided in the vacuum chamber, and work support means for supporting works arranged so as to surround the rod-like evaporation source. The vacuum chamber comprises a lower lid mounted on the work support means and a chamber body having the rod-like evaporation source fixed thereto, the lower lid being liftable relative to the body.
When recovering treated works in this device, the lower lid is lowered from the chamber body in a position not interfering therewith, and the work support means is horizontally moved from the lower lid to a recovery area. When supplying untreated works into the vacuum chamber, the untreated works are mounted on the work support means after recovery, the work support means is moved to above the lower lid, and the lower lid is raised and airtightly connected to the chamber body.
In this patent publication is also described, as another device form, a vacuum evaporator comprising a vacuum chamber, a rod-like evaporation source provided liftably into and out of the vacuum chamber, and work support means for supporting works arranged so as to surround the rod-like evaporation source, in which the vacuum chamber has an opening part airtightly openable by an opening and closing door. In this evaporator, the work support means loaded with the works can be moved in and out of the vacuum chamber through the opening part after the evaporation source is raised and retreated out of the vacuum chamber.
When recovering treated works in this device, the opening and closing door is opened after the evaporation source is raised and retreated out of the vacuum chamber, and the work support means is horizontally moved out of the vacuum chamber from the opening part. When supplying untreated works into the vacuum chamber, the untreated works are mounted on the work support means after recovery, and moved and housed in the vacuum chamber, and the opening and closing door is closed.
In each type of vacuum evaporator described above, the work support means generally has a rotary table rotating with works on board in order to uniformly coat the circumferential surface of the works, and the rotary table is driven by a drive mechanism provided on the lower lid side of the vacuum chamber.
The lower lid-raising/lowering type vacuum evaporator requires a large-scale lifting device in order to raise and lower the lower lid mounted on the work support means, and also a large lifting space. Further, the device structure becomes complicated because it is necessary to make the work support means movable from the lower lid and to interlock and connect the driving mechanism with the rotary table every recovery and supply of works.
On the other hand, in the evaporation source-raising/lowering type vacuum evaporator, the device structure also becomes complicated because it is necessary to move the work support means in and out of the vacuum chamber, although the large-scale lifting device or lifting space as in the above vacuum evaporator is not required.
Each type of vacuum evaporator has the problem of poor workability because of a limited working space in the cleaning of the inner surface of the vacuum chamber or the maintenance of various members such as anode provided in the vacuum chamber.